A dc converter of this type has been described in detail in DAS No. 1,244,281. Such dc converters operate with relatively minor losses up to about 300 volts. With higher voltages, however, the decisive question is whether during the load alternation from one transistor switching stage of the push-pull oscillator to the other, the closing transistor switching stage is already in a complete-blocking state prior to the starting of the current flow with the opening transistor switching stage. Even minimal overlappings on opening and closing the transistor switching stages result in a short-circuit current flow through both transistor switching stages, which current, under high voltage loads, is correspondingly high and results in the destruction of transistors. Increasing the dwell time between closing and opening the transistor switching stages, however, is connected with a corresponding output loss and therefore represents a drawback.
A primary object of the invention is to solve the above difficulties by providing a dc converter for high input voltages, which operates with minimal additional apparatus input and under low-loss conditions.